Multi-Gas Detector Selection Guide

Free source-aware multi-gas detector planning screen for safety managers, instrument technicians, and procurement teams. Select local hazard prompts and see which common four-gas blind spots may require additional review. Outputs are not a purchase specification, calibration procedure, bump-test record, confined-space permit, hot-work authorization, alarm-setpoint approval, or emergency-response instruction.

Pro Tip: Treat four-gas output as a selected-hazard screen only. Actual detector selection still depends on current SDS/process review, previous contents, gas stratification, sample method, selected make/model/manual, sensor part numbers, correction factors, pump/tubing, calibration gas, bump/cal records, alarm actions, employer program, and qualified safety/manufacturer review.

Look up cross-sensitivity factors for your sensor configuration

Gas Detector Cross-Sensitivity Calculator →

Review LEL/UEL for your combustible gas hazards

LEL/UEL Lookup →

Size ventilation for confined spaces

Confined Space Ventilation Calculator →

Look up chemical exposure limits for your target gases

Chemical Exposure Limits Lookup →

How It Works

Identify Hazard Prompts

Select atmospheric hazard prompts from SDS, process, previous-content, confined-space, hot-work, and site reviews. The preset list is not a job hazard analysis.
Specify Application Context

Indicate whether the screen is for personal, area, pre-entry, or continuous monitoring context. Employer procedures and applicable regulations control actual testing and authorization.
Review Sensor Prompts

Use the output to identify possible four-gas blind spots and additional sensor-review prompts. Verify every channel against the selected instrument manual and hazard assessment.
Reconcile Sources

Before purchase or use, reconcile detector approvals, pump/tubing, sample delay, alarm settings, bump/cal records, correction factors, maintenance, training, and emergency actions with qualified review.

Built For

Safety managers creating a detector review checklist before manufacturer or IH review
Procurement teams documenting which hazards need instrument-manual confirmation
Confined-space program administrators separating detector prompts from entry authorization
Oil and gas safety coordinators flagging VOC, H2S, SO2, LEL, and inert-gas review gaps
General industry safety professionals identifying when four-gas channels may miss selected hazards

References

OSHA/eCFR 29 CFR 1910.146 confined-space source pointers
OSHA atmospheric testing and pre-entry checklist context
ISA combustible-gas detector standards committee source pointer
Manufacturer manual and response-factor source pointers for selected detector families

Frequently Asked Questions

What is the standard four-gas detector configuration?

A common four-gas monitor has O2, LEL, CO, and H2S channels, but the exact sensors, calibration gas, correction factors, alarm settings, pump/sample method, and acceptable use are instrument- and program-specific. Do not treat a four-gas screen as entry approval.

When should PID or extra toxic-gas channels be reviewed?

Review PID or extra toxic-gas channels when SDS/process review, previous contents, solvents, fuels, chemical intermediates, decomposition products, or site history indicate hazards beyond O2/LEL/CO/H2S. PID response factors and electrochemical cross-sensitivities are model-specific.

Pump or diffusion: which is better?

Pump, diffusion, sample line, tubing material, response time, stratification, and sample-point sequence depend on the space and employer procedure. Follow the selected instrument manual, confined-space program, and entry supervisor requirements.

How often must I bump test and calibrate?

Use the selected manufacturer instructions, employer program, docking-station records, calibration gas shelf life, sensor condition, and applicable requirements. This screen does not set a universal bump-test or calibration interval.

Disclaimer: This tool is a preliminary source-aware planning screen only. It is not a detector purchase specification, calibration or bump-test procedure, alarm-setpoint approval, confined-space permit, hot-work permit, exposure assessment, respiratory-protection decision, emergency-response instruction, or compliance determination. Verify with current hazard assessment, SDS, employer procedures, instrument manufacturer, and qualified safety/IH review.

Learn More

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Gas Detector Cross-Sensitivity Explained

How response factors and interfering gases affect detector readings, with source-boundary, calibration, and manufacturer-manual warnings.

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Oxygen Displacement Source-Gap Guide

Uniform oxygen displacement math, gas-density prompts, detector limits, confined-space source gaps, and qualified-review boundaries.

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H2S Detection and Safety Guide

Hydrogen sulfide source-boundary guide covering OSHA, NIOSH, and ACGIH exposure rows, odor limits, detector-review boundaries, and emergency-response caveats.

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